Physics - October 2007

The terminal speed of a sky diver is 160 km/h in the spread-eagle position and 315 km/h in the nosedive position. Assuming that the diver's drag coefficient C does not change from one position to the other, find the ratio of the effective cross-sectional area A in the slower position to that in the faster position.


This is the answer:
3.8759765625


I just need to see how to get to the answer, I know it's simple, but I think I'm missing something THANKS :)

2007-10-08 09:58:17 · 2 answers · asked by Anonymous

2007-10-08 09:37:31 · 5 answers · asked by Richard S 3

A 4.0 kg block is pushed 4.2 m up a rough 37° inclined plane by a horizontal force of 75 N. If the initial speed of the block is 2.2 m/s up the plane and a constant kinetic friction force of 25 N opposes the motion, ­calculate the following.

a) the initial kinetic energy of the block
=....J
(b) the work done by the 75 N force
=....J
(c) the work done by the friction force
=....J
(d) the work done by gravity
=....J
(e) the work done by the normal force
= 0 J
(f) the final kinetic energy of the block
=....J

2007-10-08 09:19:39 · 1 answers · asked by Nikita 1

2007-10-08 09:16:25 · 1 answers · asked by tchem 1

2.75 hours, what is the flight distance between St. Louis and Boston?

2007-10-08 09:03:35 · 2 answers · asked by Lisa L 1

They're like penduloms but with a bunch of other little balls. When one hits the other ball it goes back in a cycle. What are they called? (No it's not a trivia question)

2007-10-08 08:59:16 · 2 answers · asked by Anonymous

It is non-magnetic, and marked "18-10 Stainless Steel"

2007-10-08 08:45:35 · 2 answers · asked by slimCODE 1

i need help finding a good title for my lab report, which is due tomorrow.
the example title that my teacher gave me was "Quantitative Analysis of An Object Moving with Constant Velocity"
which sounds pretty good compared to anything i came up with...any ideas? thanks

2007-10-08 08:45:08 · 1 answers · asked by Anonymous

reach pluto? The speed of light is 3.00 x 10^5km/s

2007-10-08 08:41:13 · 1 answers · asked by Anonymous

2007-10-08 08:14:36 · 2 answers · asked by Anonymous

Is it "atom"?
is it "compound"?
is it "element"?
or "molecule"?

2007-10-08 08:06:49 · 15 answers · asked by Anonymous

I know the answer(from back of book) but I can't solve for it please help

a slab of mass m1 = 21 kg rests on a frictionless floor, and a block of mass m2 = 9 kg rests on top of the slab. Between block and slab, the coefficient of static friction is 0.30, and the coefficient of kinetic friction is 0.20. The block is pulled by a horizontal force of magnitude 58 N. What is the acceleration of the slab?

2007-10-08 07:49:12 · 5 answers · asked by Anonymous

A 250 kg piano slides 4.2 m down a 30° incline and is kept from accelerating by a man who is pushing back on it parallel to the incline. The effective coefficient of kinetic friction is 0.40.

(a) Calculate the force exerted by the man.
= 376.295 N

(b) Calculate the work done by the man on the piano.
= -1580.439 J

(c) Calculate the work done by the friction force.
= -3564.561 J

(d) What is the work done by the force of gravity?
= ... J

(e) What is the net work done on the piano?
= ... J


I got the first 3 questions; however, how do i find the work done by the force of gravity???????????????
i am so confused . i don't get it so PLEASE HELP!!!!!
I can't solve for the last one, unless if i find the work done by the force of gavity...

2007-10-08 07:31:05 · 3 answers · asked by Nikita 1

2007-10-08 07:06:34 · 2 answers · asked by Anonymous

An adventurous archaeologist crosses between two rock cliffs, with a raging river far below, by slowly going hand-over-hand along a rope stretched between the cliffs. He stops to rest at the middle of the rope. The rope will break if the tension in it exceeds 2.50 x 10^4 N, & his mass is 90 kg.

(a) If the angle theta is 10.0°, find the tension in the rope.

(b) What is the smallest value the angle can have if the rope is not to break?

2007-10-08 06:47:30 · 1 answers · asked by Johnny 1

A person is walking and causes a mop to have two displacements. The first has a magnitude of 170 cm and makes an angle of 130 degrees with the positive x-axis. The resultant displacement has a magnitude of 173 cm and is directed at an angle of 17.7 degrees to the positive x-axis. How can I find the magnitude of the second displacement?

2007-10-08 06:07:53 · 2 answers · asked by tanya 1

2007-10-08 06:05:12 · 1 answers · asked by Kelly 3

PLEASE PLEASE PLEASE HELP me to do these PHYSICS questions, Thanks :)


1. a) If the KE of an arrow is quadrupled, by what factor has its speed increased?

b) If the speed is tripled, by what factor does its KE increase?

2. How much work must be done to stop a 1070 kg car traveling at 111 km/h?

3. One car has twice the mass of a second car, but only half as much kinetic energy. When both cars increase their speed by 5.5 m/s, they then have the same kinetic energy. What were the original speeds of the two cars?

first car=.....m/s
second car=.....m/s

2007-10-08 05:54:45 · 4 answers · asked by Nikita 1

Does the force that your hand exerts on the bag's handle do any work?Explain

2007-10-08 05:35:40 · 2 answers · asked by bc 1

Does the mass of an object change if it's speed also changes? EXPLAIN????

2007-10-08 04:54:34 · 4 answers · asked by Anonymous

let's say we drop a ball from a height of 1meter. Now, if we suppose that the force between the earth and the ball before dropping=9.8Newtons.According to the law of gravitation, the less the distance between 2 objects , the more the gravitational force between them. So after dropping the ball, the distance gradually decreases.So, wouldn't the force also increase?EXPLAIN????

2007-10-08 04:49:19 · 2 answers · asked by Anonymous

2007-10-08 04:41:24 · 3 answers · asked by Anonymous

If you were to look at the spectrum of the gas flame of a stove or the blue part of a Bunsen burner flame, what sort of spectrum would you expect to see—Absorption, emission, or continuous? Why?

2007-10-08 04:12:33 · 1 answers · asked by Anonymous

Suppose that you don't know the relation,
mechanical work W=F.S.

In this circumastances can you derive the equation Ek=1/2mv^2 (without using the relation W=F.S)?

I think any of the two relation (W=F.S and Ek=1/2mv^2) is axiomatic and they are circular. So that you can't get one of them without using the other. When one of them is defined axiomaticaly you can get the other.
Am I correct? please inform me!!

2007-10-08 03:03:34 · 1 answers · asked by Anonymous

If I am travelling North - South at about the speed of light, and somebody else is approaching me South - North also at about the speed of light, what is our converging speed? And how do you derive it?

2007-10-08 02:23:19 · 9 answers · asked by Anonymous

2007-10-07 23:29:30 · 10 answers · asked by William Scheef Jr. 2

2007-10-07 23:27:19 · 3 answers · asked by chrln_buenaventura 1

I understand the way we see colour but what i dont understand is why certain things absorb & reflect certain types of light is it what the are made of? Like the elements or has it got to do with something else? Like whatever it is that makes the plants green (i forget what its called) it absorbs red & blue light but reflects green light, why? is it just because that the way it is?

2007-10-07 23:26:17 · 3 answers · asked by asphyxia 3

please help me by 7:30

2007-10-07 23:21:26 · 5 answers · asked by hi 1

A student wants to determine the coefficients of static friction and kinetic friction between a box and a plank. She places the box on the plank and gradually raises one end of the plank. When the angle of inclination with the horizontal reaches 34o, the box starts to slip, and it then slides 2.7 m down the plank in 1.7 s at constant acceleration. What are (a) the coefficient of static friction and (b) the coefficient of kinetic friction between the box and the plank?

2007-10-07 22:59:25 · 2 answers · asked by Anonymous